Premium
Viscoelastic properties of polyacrylonitrile terpolymers during thermo‐oxidative stabilization (cyclization)
Author(s) -
Suresh K. I.,
Thomas K. Saji,
Rao. B. S.,
Nair C. P. Reghunadhan
Publication year - 2008
Publication title -
polymers for advanced technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.61
H-Index - 90
eISSN - 1099-1581
pISSN - 1042-7147
DOI - 10.1002/pat.1042
Subject(s) - polyacrylonitrile , materials science , dynamic mechanical analysis , viscoelasticity , copolymer , glass transition , polymer , thermal analysis , polymer chemistry , thermal , chemical engineering , composite material , thermodynamics , physics , engineering
A study on the thermo‐oxidative stabilization (cyclization) of polyacrylonitrile (PAN) terpolymers using dynamic mechanical thermal analysis (DMTA) is reported in this article. When the changes in viscoelastic properties were monitored in a rectangular tension mode, besides the tan δ peak characteristic of the glass transition observed below 200°C, the copolymer and the terpolymer displayed a second peak above 200°C due to the cyclization leading to the formation of ladder structures. The initiation temperature of the cyclization process as well as the peak temperature is found to depend on the acid value and the composition of the precursor polymer. The results presented show that monitoring the changes in viscoelastic properties during cyclization provides insight into the material properties as a result of the chemical changes that are taking place. These observations were confirmed by structural characterization using IR spectroscopy, and the observed chemical changes agree with the literature studies, as due to the thermal cyclization process. Copyright © 2008 John Wiley & Sons, Ltd.